Feed mechanism



. n 1939. D. GURIQEY ET AL 2,142,506

FEED MECHAN ISM Filed Feb. 24, 1937 2 Sheets-Sheet l INVENTOR 0 Danny.Gummy amenn L. 01'7"v ATTORNEY Jan. 3, 1939. D. G)URNEY ET AL FEEDMECHANISM '2 Sheets-Sheet 2 Filed Feb. 24, 1937 "M W w wfw Tn N m wl. hR.v wm am 7 I A of said carriage.

Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE FEED MECHANISMPennsylvania Application February 24, 1937, Serial No. 127,550

7 Claims.

Our invention relates to a feed mechanism for grinding machines or othermachine tools.

It is an object thereof to provide a feed mechanism of the pawl andratchet type which is actuated independently of any traverse movementbetween the work and wheel.

A further object is to provide a feed cam having a plurality of lobes,one or more of which may be provided with means for varying its lift.

A further object is to provide means whereby the cam follower maytransmit impulses only from preselected lobes on the feed cam.

A further object is to provide means for automatically starting saidfeed mechanism when the headstock spindle begins to rotate.

A further object is to provide means for automatically changing from aroughing feed to a finishing feed.

Our invention consists essentially of a motor driven multi-lobe camoperably connected to a pawl and ratchet type feed mechanism.

Figure l is a plan View of a grinding machine in which my invention isincorporated.

Figure 2 is a front elevation of our device partly in section.

Figure 3 is a partial front elevation showing the mechanism in finishfeed position.

Figure 4 is a diagrammatic sketch of the control mechanism of ourinvention.

On the drawings Figures 1 and 2, numeral l indicates the bed of themachine. The carriage II is mounted on said bed. The wheel support I2 ismounted on said carriage movable in a direction transverse to thedirection of movement The grinding wheel |3 is rotatably mounted on saidwheel support. The piston M in cylinder I5 is mounted on carriage II. Anelongated piston rod I6 is partially threaded to run in nut H, which isattached to wheel support 2. An adjustable stop l8 limits the range ofmovement of said piston. Said piston provides a rapid feed orpositioning movement of the grinding wheel. The hand wheel end of thefeed screw is splined to permit relative axial movement between theparts. The grinding or slow feed is provided by pawl and ratchetoperated hand wheel IS. The ratchet 20 is actuated by pawl 2|, whichconsists of an arm to which is removably attached a hardened strip 22for enigaging the ratchet teeth. The said pawl is pivotally mounted onanother arm 23, which in turn is pivotally mounted on carriage H at apoint 24 under the hand wheel I9. A spring 25, one end of which isattached to the pawl 2 I, and the other to arm 23, urges strip 22 intooperative engagement with the teeth of ratchet 20. An upright element 26carries an adjusting screw Zl, which acts as a stop to the idle movementofpawl 2|. Pawl 2| and arm 23 carry stop elements 28 and 29,respectively, which are identical in shape. 5

When strip 22 is in contact with ratchet 2B the stops 28 and 29 areslightly out of alignment, with stop 28 in advance of stop 29 in thedirection of screw 21. During the idle movement stop 28 engages screw2'! and the pawl 2| is given a slight rotating movement until stop 29engages said screw, at which time the stops are in alignment and furtherrelative movement between them is prevented. This slight rotary movementof pawl 2! is sufficient to lift strip 22 out of contact with ratchet20.

One end of a link 3| is rotatably attached to arm 23, the other end issupported by a link 32 which is suspended from the armature 33 of thesolenoid 34. This solenoid is mounted in an inverted position in ahousing 35. Intermediate the ends of said link 3| are a shoulder 36 anda lug 3'! which carries a screw 38. This screw is adjustable relative toshoulder 36. A spring 39 one end of which is attached to link 3|, and25.

carries a pin 42 which projects laterally therefrom into the path ofmovement of either shoulder 36 or screw 38. A second arm 43 is alsokeyedto the shaft 4| and carries. a roller follower 44. Aspring 45, havingone end attached to arm 43 and the other to a housing 72, holds saidroller in contact with a multilobe cam 46. Said cam is secured to ashaft 41 in housing 12 and said shaft is driven through suitable gearingby a motor 48. One or more of the lobes of said cam may be madeadjustable by inserting screws 49 therein.

It is desirable to have pawl 2| in the withdrawn position when feedmotor 48 stops. To accomplish this a switch 80 is mounted in such aposition relative to the cam 46 that it will be opened when the roller44 is at a low point on the cam. Said switch may be placed in a branchline 3! from the normally open contact of switch 55. Said element 26,also, carries an arm 33, which 0 extends therefrom and contacts with theperiphery of hand wheel l9 and acts as a brake thereon, preventing saidhand wheel from acting as a fly wheel. Said arm also acts as anindicator for the graduations on said hand wheel.

Operation The operator moves the wheel carriage longitudinally by meansof lever 15 to place the grinding wheel inside the work. In response tothis movement, cam 5I on said carriage closes a switch 52 which is thesupply line to the headstock motor 50. The supply line consists of twowires 53 and 54. All the electrical control mechanism is supplied fromthis source and line 54 through its branches 54a, 54b and 540 is thecommon return line. Upon closing the switch 52, the headstock motor 58is started. At the same time feed motor 48 is started through two polerelay 55 which is in normal position as shown. Movement of the carriageis utilized as described in Gurney Patent 2,064,427 granted December 15,1936, to direct a supply of fluid under pressure to line 56 and valve51. This valve may be shifted in one direction by spring 58 and in theother direction by solenoid 59, to direct fluid under pressure to oneside or the other of piston I4. In the position shown in Figure 4,solenoid 59 is tie-energized and valve 51 will direct fluid underpressure through passage 60 to cylinder I5 and shift piston I4 to movethe grinding wheel I3 into contact with the work piece. The switch 52 isalso effective through the switch 55 shown in normal position, to startfeed motor 48; said motor through a suitable transmission mechanismrotates feed cam 46 which acts. through a follower 44 and associatedparts described above to deliver feed impulses to wheel feed hand wheelI9 through pawl 2| and ratchet 20. Viith the parts in the position shownin Figure 2, each lobe of the cam actuates ratchet 20 so that saidratchet receives six impulses for every revolution of the cam.

The progress of the grinding operation may be controlled by any suitablesizing device. We prefer to use the type disclosed in the abovementioned Gurney patent, and, also, in Balsiger Patent 2,001,447,granted May 14th, 1935. A portion of one of these devices sufiicient tounderstand its function in this application is shown in Figure 4. Itconsists of a section of a manometer tube 63 having a series ofelectrical contacts, 64, 65 and 66, which may be connected through abody of mercury 61 or other electrically conductive substance.

As the grinding operation proceeds the mercury rises in the tube asdescribed in the above mentioned patent until contacts 64 and 65 areboth covered, thus completing a circuit to solenoid 34 and line 54, 54aand 54c. This solenoid upon being thus energized acts through link 32 tolift arm 3| so that pin 42 will contact screw 38 instead of shoulder 36.The difference in position between the shoulder and the screw may bevaried so that only those lobes having a high lift will be effective toactuate ratchet 20. The arm 40 will be oscillated by the other lobes butthe movement will not be great enough to cause pin 42 to engage and movescrew 38. Even those lobes having a high lift will transmit a shorterimpulse to the feed pawl. Thus, feed impulses will be reduced in bothfrequency .and magnitude thereby providing an extremely fine feedmovement for the grinding wheel. The grinding operation continues untila further pre-determined size is reached when the mercury engagescontact 66 energizing relay coil 68. Said coil operates the relaycontacts to open the circuit to the feed motor 48 and to close thecircuit to the timing mech- .anism 69, thus stopping the feedingmovement and setting in motion the mechanism for separating the wheeland the work. When the circuit to the timing mechanism is closed currentalso passes through branch line ill to keep motor 48 running until cam48 has reached a position to permit withdrawal of pawl 2|. At this pointone of the lobes of said cam operates switch 80 to stop said motor. Ifnecessary a dynamic brake 82 of any suitable type may be utilized tostop the feed motor and cam more quickly. After a pre-determinedinterval said timer will close switch I0 to energize solenoid 59. Saidsolenoid will then shift valve 51 to a position to direct fluid underpressure to the right hand end of the cylinder I5, move piston I4 to theleft end, and thus back off wheel I 3 from the work. The work and wheelmay then be separated axially and the separating movement will beeffective through cam 5I to open the circuit to the headstock motor 5through switch 52.

Various changes may be made in our device without departing from thespirit of the invention, therefore, we do not wish to be limited to thestructure disclosed in the specifications and drawings but only as setforth in the appended claims.

We claim:

1. In a device of the kind described, a wheel support, a work support,mechanism for causing a relative feeding movement between said supports,a multiple lobe cam for causing intermittent movement of said feedmechanism, means for driving said cam, and means for rendering one ormore of said lobes ineffective to operate said feed mechanism.

2. In a device of the kind described, a wheel support, a work support,mechanism for causing a relative feeding movement between said supports,a multiple lobe cam for causing intermittent movement of said feedmechanism, means for driving said cam, means for rendering one or moreof said lobes ineffective to operate said feed mechanism, and means forvarying the effective lift of one or more of said lobes.

3. In a device of the kind described, a work support, a wheel support,mechanism for causing a relative feeding movement between said supports,a cam for actuating said mechanism, a separate motor for driving saidcam, and means for varying the magnitude and frequency of the feedimpulses while maintaining a constant speed of said motor.

4. In a device of the kind described, a work support, a wheel support,means for effecting a feeding movement between said supports, mechanismfor actuating said feeding means comprising a rotatable cam and meansfor rotating same, and means responsive to a change in size of a workpiece for varying the magnitude and frequency of the feed impulsescaused by said cam independently of said rotating means.

5. In a device of the kind described, a Wheel support, a work support,mechanism for causing a relative feeding movement between said supports,a multiple lobe cam for causing intermittent movement of said feedmechanism, means for adjusting one or more of said lobes to provide agreater lift than the rest, automatic means for rendering the unadjustedlobes ineffective to operate said feed mechanism whereby to reduce thefrequency of feed impulses.

6. A feeding mechanism for a machine tool including a tool support, awork support, mechanism for causing a relative feeding movement betweensaid supports, means for causing intermittent movement of said feedmechanisms, including a 76 I multiple lobe cam, means for adjusting oneor more of said lobes to provide a greater lift than the rest, andautomatic means to transmit feed impulses from said cam which correspondto the difference in lift between the adjusted and the unadjusted lobes.

7. A grinding machine comprising a wheel support, a work support, a feedmechanism for effecting a relative feeding movement between saidsupports including a pawl and ratchet mechanism,

means for actuating said pawl and ratchet mechanism including a multiplelobe cam, part of the surface of said cam causing engagement betweensaid pawl and ratchet and another part of said cam permitting separationof said pawl and ratchet, a motor for driving said cam and means forstopping said motor when said pawl and ratchet are separated.

DANIEL GURNEY.

CONRAD L. OTI.

